Conventionally, a liquid display device or a display device of an active matrix driving type such as an organic electro luminescence (EL) display device includes a thin-film transistor called a TFT.
In general, display device on the market includes thin-film transistors having semiconductor layers made of silicon. In recent years, organic thin-film transistors having semiconductor layers made of organic materials have been focused on. Organic materials have characteristics of being flexible because of molecular coupling by intermolecular attraction dissimilar to atomic coupling in the case of a silicon crystal. Accordingly, use of organic thin-film transistors makes it possible to realize electric devices which are lighter, thinner, and more flexible than electric devices including silicon thin-film transistors. For this reason, applications of organic thin-film transistors to next-generation display devices, electric paper, etc. have been proposed. For example, Patent Literature 1 discloses organic thin-film transistors of a bottom gate type.
FIG. 31 is a cross-sectional view of a structure of a conventional organic thin-film transistor. As shown in FIG. 31, the conventional organic thin-film transistor 100 includes the following formed sequentially above a substrate 101: a gate electrode 102; a gate insulator 103; a pair of a source electrode 104S and a drain electrode 104D; a partition wall part (bank) 106 above the gate electrode 102; and an organic semiconductor layer 107 formed in an opening of the partition wall part 106 using an ink jet method. Furthermore, a protection film 108 is formed above the organic semiconductor layer 107, and an interlayer insulator 109 is formed to cover the protection film 108.